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   1  <?php
   2  
   3  /**
   4   * Custom validation class, accepts DTD child definitions
   5   *
   6   * @warning Currently this class is an all or nothing proposition, that is,
   7   *          it will only give a bool return value.
   8   */
   9  class HTMLPurifier_ChildDef_Custom extends HTMLPurifier_ChildDef
  10  {
  11      public $type = 'custom';
  12      public $allow_empty = false;
  13      /**
  14       * Allowed child pattern as defined by the DTD
  15       */
  16      public $dtd_regex;
  17      /**
  18       * PCRE regex derived from $dtd_regex
  19       * @private
  20       */
  21      private $_pcre_regex;
  22      /**
  23       * @param $dtd_regex Allowed child pattern from the DTD
  24       */
  25      public function __construct($dtd_regex) {
  26          $this->dtd_regex = $dtd_regex;
  27          $this->_compileRegex();
  28      }
  29      /**
  30       * Compiles the PCRE regex from a DTD regex ($dtd_regex to $_pcre_regex)
  31       */
  32      protected function _compileRegex() {
  33          $raw = str_replace(' ', '', $this->dtd_regex);
  34          if ($raw{0} != '(') {
  35              $raw = "($raw)";
  36          }
  37          $el = '[#a-zA-Z0-9_.-]+';
  38          $reg = $raw;
  39  
  40          // COMPLICATED! AND MIGHT BE BUGGY! I HAVE NO CLUE WHAT I'M
  41          // DOING! Seriously: if there's problems, please report them.
  42  
  43          // collect all elements into the $elements array
  44          preg_match_all("/$el/", $reg, $matches);
  45          foreach ($matches[0] as $match) {
  46              $this->elements[$match] = true;
  47          }
  48  
  49          // setup all elements as parentheticals with leading commas
  50          $reg = preg_replace("/$el/", '(,\\0)', $reg);
  51  
  52          // remove commas when they were not solicited
  53          $reg = preg_replace("/([^,(|]\(+),/", '\\1', $reg);
  54  
  55          // remove all non-paranthetical commas: they are handled by first regex
  56          $reg = preg_replace("/,\(/", '(', $reg);
  57  
  58          $this->_pcre_regex = $reg;
  59      }
  60      public function validateChildren($tokens_of_children, $config, $context) {
  61          $list_of_children = '';
  62          $nesting = 0; // depth into the nest
  63          foreach ($tokens_of_children as $token) {
  64              if (!empty($token->is_whitespace)) continue;
  65  
  66              $is_child = ($nesting == 0); // direct
  67  
  68              if ($token instanceof HTMLPurifier_Token_Start) {
  69                  $nesting++;
  70              } elseif ($token instanceof HTMLPurifier_Token_End) {
  71                  $nesting--;
  72              }
  73  
  74              if ($is_child) {
  75                  $list_of_children .= $token->name . ',';
  76              }
  77          }
  78          // add leading comma to deal with stray comma declarations
  79          $list_of_children = ',' . rtrim($list_of_children, ',');
  80          $okay =
  81              preg_match(
  82                  '/^,?'.$this->_pcre_regex.'$/',
  83                  $list_of_children
  84              );
  85  
  86          return (bool) $okay;
  87      }
  88  }
  89  
  90  // vim: et sw=4 sts=4